Amylyx director buys 3,800 shares in open market

Amylyx Pharmaceuticals director Karen Firestone made an open-market purchase of the company’s Common Stock.

Rhea-AI Filing Summary

Amylyx Pharmaceuticals director Karen Firestone made an open-market purchase of the company’s Common Stock. On May 21, 2026, she bought 3,800 shares at a price of $13.51 per share. Following this transaction, she directly owns 66,900 shares of Amylyx common stock.

Insider Trade Summary

Net Buyer: 3,800 shares

Net Buy 1 txn

Insider Firestone Karen

Role Director

Bought 3,800 shs ($51K)

Type	Security	Shares	Price	Value
Purchase	Common Stock	3,800	$13.51	$51K

Holdings After Transaction: Common Stock — 66,900 shares (Direct)

Key Figures

Shares purchased: 3,800 shares Purchase price: $13.51 per share Shares owned after: 66,900 shares +1 more

4 metrics

Shares purchased 3,800 shares Open-market purchase on May 21, 2026

Purchase price $13.51 per share Price for Common Stock on May 21, 2026

Shares owned after 66,900 shares Direct holdings following the transaction

Net shares bought 3,800 shares Net buy in this Form 4

Key Terms

open-market purchase, Common Stock, Form 4

3 terms

open-market purchase financial

"she bought 3,800 shares at a price of $13.51 per share in an open-market purchase"

An open-market purchase is when an investor or a company buys shares on a public stock exchange at the going market price, rather than through a private deal. It matters to investors because these purchases change how many shares are available, can push the stock price up or signal confidence from large buyers, and often affect per-share metrics like earnings—think of it like someone buying lots of apples off a grocery shelf, reducing supply and potentially raising the price.

Common Stock financial

"made an open-market purchase of the company’s Common Stock"

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

Form 4 regulatory

"according to a new Form 4 filing"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Amylyx Pharmaceuticals (AMLX) report for Karen Firestone?

Amylyx reported that director Karen Firestone completed an open-market purchase of its Common Stock. She bought 3,800 shares on May 21, 2026 at a price of $13.51 per share, increasing her direct holdings.

How many Amylyx (AMLX) shares did Karen Firestone buy and at what price?

Karen Firestone bought 3,800 shares of Amylyx Common Stock in an open-market transaction. The shares were purchased at an average price of $13.51 per share, as disclosed in the Form 4 insider trading report.

What are Karen Firestone’s total Amylyx (AMLX) holdings after this transaction?

After the reported transaction, director Karen Firestone directly holds 66,900 shares of Amylyx Pharmaceuticals Common Stock. This figure reflects her position immediately following the 3,800-share open-market purchase on May 21, 2026.

Was the recent Amylyx (AMLX) insider transaction a purchase or a sale?

The reported insider transaction was a purchase. Director Karen Firestone conducted an open-market purchase of 3,800 shares of Amylyx Common Stock at $13.51 per share, according to the Form 4 filing details.

Is Karen Firestone’s Amylyx (AMLX) ownership direct or indirect after the trade?

Karen Firestone’s reported holdings are direct ownership. The Form 4 identifies the 66,900 shares she holds after buying 3,800 shares on May 21, 2026, as directly owned Common Stock in Amylyx Pharmaceuticals.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/26/2026 - 04:00 PM EDT Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Firestone Karen

(Last) (First) (Middle)

C/O AMYLYX PHARMACEUTICALS, INC.

55 CAMBRIDGE PARKWAY, SUITE 6W

(Street)

CAMBRIDGE MASSACHUSETTS 02142

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Amylyx Pharmaceuticals, Inc. [ AMLX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/21/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	05/21/2026		P		3,800	A	$13.51	66,900	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

	/s/ Joshua B. Cohen, as Attorney in Fact	05/26/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)